Which factor is least likely to influence the usability of a product?

The factor that is least likely to influence the usability of a product is production cost. Usability primarily focuses on how effectively the end user can interact with and benefit from a product. It encompasses aspects such as ease of use, functionality, and user experience. While production cost is a crucial consideration for manufacturers and can affect the overall design process, it does not directly impact how a user engages with the product itself.

On the other hand, the quality of materials, design robustness, and maintenance considerations all play significant roles in usability. High-quality materials can enhance the user's experience by ensuring the product functions well and lasts longer. Design robustness contributes to the reliability and user confidence in the product. Maintenance considerations can affect the ease of upkeep and how well users can maintain the product's performance over time. Thus, while production cost is important in the broader context of product development and business viability, it is the factor least associated with the usability experienced by the end user.